I created a small video with
threshold filter to get black and white pixels (no greyscale):
ffmpeg -y -i /dev/video0 -f lavfi -i color=0x606060:s=640x480 -f lavfi -i color=black:s=640x480 -f lavfi -i color=white:s=640x480 -filter_complex threshold -c:v libx264 -c:a copy test.mp4
Then I tried to convert it as a APNG file with white pixels as transparent (
ffmpeg -y -i test.mp4 -f apng -vf chromakey=white test.apng
This command converts all the pixels into transparent (checked with Gimp, it sets alpha of all pixels to 0).
Why? Also, how can I fix the command to make it work?